Method for producing molybdenum or molybdenum alloy gun liner



1961 s. v. c HBERT ETA 2,972,179

M on FOR nucmc MOLYBD M MOLYBDEINUM ALLOY GUN LINER Filed July 29. 1952 L IN.

INVENTORS STUART I! GUTHBERT DONALD WROUGHTON BY (Q 5 MNEYS United States Patent METHOD FOR PRODUCING MOLYBDENUM OR MOLYBDENUM ALLOY GUN LINER Stuart V. Cnthbert, North Caldwell, N.I., and Donald Wroughton, Pittsburgh, Pa., assignors, by mesne asslgnments, to the United States of America as represented by the Secretary of the Navy Filed July 29, 1952, Ser. No. 301,552

9 Claims. (Cl. 29--1.1)

The present invention relates to improvements in methods of making gun liners and more particularly to improved methods of producing molybdenum or molybdenum alloy gun liners.

An important object of the invention is to provide a method of making molybdenum or molybdenum alloy gun liners of suitable strength and hardness.

Another object of the invention is the provision of a method of making molybdenum or molybdenum alloy gun liners from rolled shapes.

A further object is to provide a method of making molybdenum or molybdenum alloy gun liners from rolled shapes and having a helical grain therein of a pitch substantially corresponding to that of rifling.

A still further object is the provision of a method of makingmolybdenum or molybdenum alloy gun liners from a pair of semicylindrical troughs.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a perspective view of a rectangular bar of molybdenum or molybdenum alloy showing the initial shape of one half of the gun liner;

Fig. 2 is a diagrammatic side elevational view illustrating a step in the rolling of the rectangular bar into a flat plate;

' Fig. 3 is a perspective view of a rolled flat plate produced from the initial rectangular shape shown in Fig. 1;

Fig. 4 is a perspective view of complementary die portions used in forging the rolled shape into a semicylindrical trough;

Figs. 5, 6 and 7 are diagrammatic views in end elevation illustrating successive forging of :1 rolled flat shape into a semicylindrical trough;

Fig. 8 is a diagrammatic fragmentary view partly in side elevation and partly in central longitudinal section showing the assemblage of a pair of troughs on a tungsten rod and clamped in a twisting device;

Fig. 9 is a fragmentary side view of a twisted seam liner formed by the hereindescribed method;

Fig. 10 is a diagrammatic front elevational view illustrating a step in the rolling of a rectangular bar into a reduced rectangular shape; and

Fig. 11 is a diagrammatic view in end elevation illustratingthe forging of the rolled rectangular shape of Fig. 10 into a semicylindrical trough.

In Figs. 1-8 of the drawing is illustrated a method of making a'gun liner from square or rectangular bars rolled flat and then forged to form troughs.

For the production of caliber .50 gun liners, the method at 18 in Fig. 3, in three steps in dies 1 21 of graduated curvature as illustrated in Figs. 4-7 to form semicylindrical troughs. After machining the shoulders of the.

Material rolling schedule 1 Pass Temperature, Thickness, Reduction, Remarks Time inches inches 1,500 0"... 1.250 0 Leveling pass. 1,500 1 000 .250 Held in furnace until 1,500 G. is reached.

1,500 C 810 190 Do. 2 minutes 720 .090 1% minutes .645 .075

1 minute 570 075 minute"- 495 075 V, 1'I1inute 435 060 }4 minute... 375 060 minute. 320 055 N0. Reheat 285 035 minutc 255 030 N o Reheat 230 025 Before forging the rolled blanks 18 into troughs, the

groove 19 of the troughing dies. This straightening may be done manually or by drop hammer on fiat dies in the temperature range of 950 to 1250 C. depending on alloy content.

After reheating, each straight flat strip 18 is laid in the first stepdie 19 and shaped rapidly before too much cooling takes place. reheated and hammered in the second step die 20. To finish the forging operation a final hammering is done in the finishing die 21.

The shoulders of the straight troughs are machined so that when placed together, two troughs 22, 23 will form a cylinder. The two halves 22, 23 are assembled, with a tungsten rod 26 therebetween, and bound together with molybdenum wire 27. The entire assembly is heated to a temperature of the order of 1100 C. to 1250 C. and then placed in coaxially aligned spaced end clamps 28, 29, one 28 being fixed. The other clamp 28 is rotated a sufi'icient number of degrees to produce in the trough assembly 25 an axial twist 3% having a pitch correspond ing substantially to that of rifling.

In Figs. 10 and 11 is shown an optional method of producing semicylindrical troughs for subsequent twisting into spiral grained cylinders as hereinbefore described using the equipment illustrated in Fig. 8. This second method consists in rolling heat treated square or rectangular bars 31 on cylindrical rolls 32, 33 from the approxiate dimensions of .75" X .875" to .60" x .375", and then forging the resultant rolled bars 31 in the finishing groove 21 of the troughing die as shown in Fig. 11. 3

For example, the following schedule was used for molybdenum plus ll0% cobalt.

consists in rolling properly heat treated squareor rectangular bars, such as the bar 15 shown in Fig. 1, having an approximate size of .875" x 1.125", to a thickness of .230, as by successive passes between pairs of cylinder rolls such as the rolls 16, 17 shown in Fig. 2, and then forging the resultant flat plates, one of which is shown ate rial rolling schedule 2 When necessary, the rectangular bars 31 are straight- The partly formed trough is then 3 ened at 1100" C. to fit the finishing die; The straight bars then are forged into trough shape by repeated hammering in the finishing trough 21 of the die used in the previously described method. The forged troughs then are matched for size, tested for physical characteristics,

or subjected to annealing or twisting as hereinbefore desemblage to a temperature of the order of 1l00 to 125 (3., and while heated approximately to said temperature, axially twisting the assemblage in a direction and to a degree such as to transform said troughs into an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of rifiing. 7

2. The method of producing a molybdenum gun liner, starting with a'pair of rolled molybdenum shapes, which consists in forging said shapes into a pair of semicylindrical troughs, encirclingly mounting said pair of troughs on a rod shaped tungsten core, to form an assemblage, heating said assemblage to a temperature of the order' of ll00 to 1250" C., and while heated approximately to said temperature, axially twisting the assemblage in a direction and to a degree'such as to transform said troughs into an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of rifting. i s

3; The method of producing a molybdenum gun liner, starting with a pair of rolled molybdenum shapes which consists in forging said 'sh'apesinto a pair of semicylindrical troughs terminating at opposite sides in shoulders, machining said shoulders to accurate conformity with said semicylindricm shape, encirclingly mounting said pair of troughs on a rod shaped tungsten core' to form an assemblage, heating said assemblage to a temperature of the'order of 1100" to 1250 C., and while heated approximately to said temperature, axially twisting the assemblage in 'a'direction and to a degree such as to transform said troughs into' an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of killing. 7

4. .Themethod of producing a molybdenum gun liner, starting with molybdenum rectangular bar stock, which consists in heating said bar stock to a temperature of. the order of1500 C., rolling said bar stock whileso heated to form a pair of rolledplates, forging said plateswhile 'stillhot' to form a pair of semicylindrical troughs, encirclingly mountingsaid pair of troughs on a rod shaped tungsten core to form an assemblage, heating said assemblage to a temperature of the order of ll00 to 1250 C., and while heated approximately to said last mentioned temperature, axially twisting the assemblage in a direction and to a'degree such as to transform said troughs into an integral tubular cylinder having a helical grain therein of a pitch substmtially corresponding to that of rifling.

5; The method of producing a molybdenum with approximately 0.1% cobalt alloy gun liner, starting with an assemblage of a pair of semicylindrical molybdenum alloy troughs encirclingly mounted on a rod; shaped tungsten core, which consists in heating said assemblage to a temheated approximately to said temperature, axially twisting the assemblage in a direction and to a degree such as to trzmsform said troughs into :an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of rifting.

6. The method of producing' a molybdenum with approximately 0.1% cobalt alloy gun liner, starting with a pair of rolled molybdenum alloy shapes, which consists in forging said shapes into a pair of semicylindrical troughs, encirclin gly mounting-said pair of troughs on a rod'shaped' tungsten core, to form an assemblage, heating said assemblage to a temperature of the order of 1100" to 1250 C., and while heated approximately to said temperature, axially twisting the assemblage in a direction and to a degree such as to transform said troughs into an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of rifiing.

7. The method of producing a molybdenum with approximately O.1% cobalt alloy gunliner, starting with a pair of rolled molybdenum alloy shapes which consists of forging said shapes into a pair of semicylindrical troughs terminating at opposite sides'in shoulders, machining said shoulders to accurate conformity with said semicylindrical shape, encirclingly mounting said pair of troughs on a rod shaped tungsten core to form an assemblage, heating said assemblage to a temperature of the order of 1100 to 1250 C., and while heated approximately to said temperature, axially twisting the assemblage in a direction and to a degree such as to transformsaid troughs into 'an'integral tubular: cylinder having a helical grain therein of a pitch substantially corresponding to that of rifting. I

' 8.- The method of producing a molybdenum withiapproximately 0.1% cobalt alloy gun liner, starting with molybdenum alloy rectangular bar stock, which consists in heatingrsaid bar stock to a temperature of'the'order of 1500 C.,rolling-said bar stock while so heated to. form a pair of rolled plates, forging said plates'while still hot to form a pair of semicylindrical; troughs, encirclingly mounting said pair of troughs on a rod shaped tungsten core to form an assemblage, heating said-assemblage to a temperature of theorder ot- 1l00 to 1250 C., and

while heated approximately to said'last mentioned tern-.

' perature, axially twisting the assemblage in a direction and to a degree such as to transform said troughs: into an integral tubular cylinder having a helicalgrain therej in ofa pitch substantially corresponding to that of rifiing.

9'. The method of producing a gun liner, starting with i a pair of rolled shapes, which consists in forging said shapes into apair of semicylindrical troughs terminating at opposite sides in shoulders, machining said shoulders to accurate conformitywith said sernicylindrical shape, encirclingly mounting said pair of troughs on a rod shaped core to form an assemblage, heating said assemblage to a proper Working temperature, and while .so heated axially twisting the assemblage in a direction and to a degree such as to transform said troughs into an integral tubular cylinder having a helical grain therein of a pitch substantially corresponding to that of rifling.

References Cited in the file of this patent UNITED STATES PATENTVS- 7,547 Pannabecker" Aug. 6, 1850 7 9,999 Warner Sept: 6, 1853 2,300,353 Eberha'rdt Oct...2 7', 1942 2,499,944 Brace et al. Mar. 7, 1950 FOREIGN PATENTS Great Britain 1896 

